1987 Merc 350 noise at high RPM, timing related

[thedillybar]

Re: 1987 Merc 350 noise at high RPM, timing related

Took it out today...same noise. Right around 3500rpm. Clicking/rattling...

 

[Bondo]

Re: 1987 Merc 350 noise at high RPM, timing related

Took it out today...same noise. Right around 3500rpm. Clicking/rattling...

Ayuh,...

Pull the Sparkplugs, line them up, in order,+ take some pictures of their working ends....

 

[KJSmitty]

Re: 1987 Merc 350 noise at high RPM, timing related

Took it out today...same noise. Right around 3500rpm. Clicking/rattling...

Well that's a bummer,,,

- Is it still effected by turning the distributor/timing adjustments - retarding the timing etc.?

- Is it a single ticking/rattle like a single piston/bearing/lifter etc.?

- Where abouts on the engine is the noise coming from?

- Under load (cruising) or while revving in neutral etc.?

- What type of fuel pump do you have - mechanical? (most tick when at idle however as well...)

-- Lastly,, any change in the clicking noise, resultant of the valve re-adjust etc.?

Hmmmmm.

 

[chiefalen]

Re: 1987 Merc 350 noise at high RPM, timing related

All mechanical fuel pumps make noise just the nature of the beast.

 

[thedillybar]

Re: 1987 Merc 350 noise at high RPM, timing related

Yeah, a bummer for sure. Made noise at 8* advanced and 4* advanced...didn't try retarding past that. I assume it's the same problem...the valve lash adjustment didn't seem to do anything whatsoever.

It sounds like multiple ticking/rattling to me...but it's awful hard to say.

Only makes the noise when under load, which makes it especially difficult to tell where it's coming from.

I think I'm going to get a stethoscope and see if I can hear anything at idle or rev'd in neutral. And take another look at the plugs.

 

[chiefalen]

Re: 1987 Merc 350 noise at high RPM, timing related

You have someone else driving while your working on the motor?

Nothing else going on, no loss of power no overheating?

No noise from the back when your turning the boat, drive is all the way down?

It making how mush rpm at wot?

And what speed?

This is a new noise or you had it all the time, even before the head work?

No water in the oil. Or drive?

Gimble bearing noise could travel. So could bad u joints in the drive.

Or it could be nothing, nada ,zilch.

All the pullies are good?

Belts good?

Alternator charging good?

 

[Maclin]

Re: 1987 Merc 350 noise at high RPM, timing related

I thought the valve lash adjustment was to fix the 4,000rpm "limit" you were experiencing and that the ticking may or may not be related. Will it rev higher now?

 

[thedillybar]

Re: 1987 Merc 350 noise at high RPM, timing related

Thanks for the thoughts.

Working on the engine while cruising would need a really calm day...and probably removing the engine hatch. Possible I guess.

No loss of power, no overheating. I haven't run it with the noise for more than a few seconds. Not sure on rpm/speed at WOT, the lake was very rough. I've never attempted to let it continue revving once the noise starts.

The u joints do make a little noise when lower unit is all the way down and turning 100% to the left or the right. Pullies, belts, alternator all good. At 8* advanced, it starts making noise around 3000rpm. But when I retard the timing it revs to 4000+ rpm and doesn't make any noise at all. I have trouble believing it's anything but the engine.

Did not have the noise before I pulled the heads. No water in oil or drive.

 

[chiefalen]

Re: 1987 Merc 350 noise at high RPM, timing related

And around, and around, we go i remember thats why i asked about who adjusted the valves originally.

Cause the heads were pulled. And had work done on them.

I'm gonna ask around here on this one and make a call or 2 don't give up.

 

[Bondo]

Re: 1987 Merc 350 noise at high RPM, timing related

2ndly,...
Detonation is caused by several things,....
1 of which I don't see mentioned anywhere here....
A Lean condition....
Are the Fuel Filters Clean,..??
How about the Carb,..??

Ayuh,... Quoted from post #11 of this thread.....

I've Still not seen any mention of verifying that it's Not going Lean at high RPMs.....
Matter of fact,... I see No mention of the fuel system, at All......

 

[chiefalen]

Re: 1987 Merc 350 noise at high RPM, timing related

Bond-o asked for a pic of the plugs, can you do that so we can see what they look like ?

Were moving on to the next thing.

 

[Bondo]

Re: 1987 Merc 350 noise at high RPM, timing related

Bond-o asked for a pic of the plugs, can you do that so we can see what they look like ?

Were moving on to the next thing.

Hmmmmm,.......

Got a Mouse in your pocket or something,..??..??..??

 

[chiefalen]

Re: 1987 Merc 350 noise at high RPM, timing related

Got to be fuel related somehow ?

Maybe a vacuum check ?

What ya think Bond-o

 

[KJSmitty]

Re: 1987 Merc 350 noise at high RPM, timing related

All mechanical fuel pumps make noise just the nature of the beast.

Maybe the nature of your beast,,,,

But I have only had two noisy/"ticking" mechanical fuel pumps personally. One on a LS6 454 and one on a 455 both were bad.

Every other noisy mech pump that entered our shop was also bad. If the actuator mechanism and spring/load is good (not to mention the cam or sprocket lobe is good), they are "silent."

Now to something relevant, - the ops noise is at higher rpms. I can say that most noisy/"bad" mechanical fuel pumps "tick" at idle (no load) as well. So this is probably not his issue.


I've had a few engines that leaned out on the top end due to jetting yet none to an extent to cause knocking etc..

Tough one to diagnose over the computer...

 

[chiefalen]

Re: 1987 Merc 350 noise at high RPM, timing related

Ticking is noise also i believe.

However some shops will replace parts to make a quick buck. Even if the part is still good. And springs can be replaced, no need for a new pump.

Not that i'm saying YOUR shop is one of them.

So back to something positive, vacuum check.

You do those in Texas ?

Might reveal alot or nothing, and heres the link.

http://www.secondchancegarage.com/public/186.cfm

 

[KJSmitty]

Re: 1987 Merc 350 noise at high RPM, timing related

I do continue to get a chuckle out of some of your posts chief.

Your reading comprehension never stops amazing me.

And yes, Texan's do perform vacuum checks - it's the best way to see if the lack of suction is due to the bag being full.. Is it the same in Jersey?

Vacuum check for diagnostic purposes: "Might reveal alot or nothing." Now that is the truth. However, I do still have one in my toolbox.

Happy Holidays!

 

[chiefalen]

Re: 1987 Merc 350 noise at high RPM, timing related

Smitty has been harder and harder nowadays to get what i read in my mind right.

I use a shop vac don't got no stikin bag.

I love Texas, my first wife i married in Tyler Texas, and my brother still lives in Waxahatchie Texas. He was the chief of surgery at a big Dallas hospital. My first job out of the service was at Dallas airport.

Fish are bigger, the wemon are meaner, and it's a BIG country down there.

If done correctly a vacuum test as many know here, will tell you secrets about your motor that you might other wise miss.

Would like to help this guy. Tough to do if you can't put ya hands on the motor.

 

[thedillybar]

Re: 1987 Merc 350 noise at high RPM, timing related

Noise disappears when I zip-tie the secondary air valve closed. Actually I hear it for 1/2 second on acceleration and then it disappears. Not sure if this is a concern or not..

Secondary rods are CLs. I'm going to set the hanger higher (richer) and then play w/ the spring tension.

 

[Bondo]

Re: 1987 Merc 350 noise at high RPM, timing related

Actually I hear it for 1/2 second on acceleration and then it disappears. Not sure if this is a concern or not..

Ayuh,...

IF it's Detonation,... It's Always Bad....

 

[thedillybar]

Re: 1987 Merc 350 noise at high RPM, timing related

It's better with the shorter (richer) secondary hangers. Still makes noise at WOT and only revs to 4000rpm not 4400.

It seems to top out at 4000rpm regardless of what the timing is set at..and regardless of whether or not the secondaries are locked out.